Memorizing the first operating time of a stand-by battery and/or indicating the end of a stand-by battery lifetime

ABSTRACT

A backup battery for buffering the operating voltage of a circuit arrangement is realized by a battery combined with an electrically irreversible element established by a melt fuse to form a unit. When the irreversible element exhibits its original condition when monitored, it is placed into the irreversible condition and the point in time is stored. As a result of the positive identification of the point in time of the initial commissioning of the backup battery, a premature replacement of the battery before expiration of the guaranteed service life that may appear necessary due to security considerations is avoidable. In a specific development, reaching the end of the service life of the backup battery is marked by the irreversible element.

[0001] The subject matter of the application is directed to a specificembodiment of a backup battery and to a method for storing the point intime of the initial commissioning of a backup battery and/or markingwhen the end of the service life of a backup battery is reached.

[0002] Electrical devices supplied from the public mains network andhaving high demands made of the availability comprise a backup batteryfor bridging a network outage that can be established by an accumulator.Since the service life of an accumulator exhibits an age-conditionedlimit, the accumulator must be replaced when the guaranteed service lifehas been reached. The point in time of the initial utilization of theaccumulator is the determining factor for monitoring the expiration ofthe guaranteed service life. Given a program-controlled interrogation ofthe operating voltage of the accumulator, first, a distinction cannot bemade between and new and an old accumulator and, second, a replacementof the accumulator carried out during a network outage cannot berecognized. As a result, the program-controlled interrogation must bebased on the worst case that is established by a required replacement ofthe accumulator.

[0003] One possibility of countering this problem is comprised incommunicating the replacement of the accumulator to some other meanswith a separate power supply such as, for example, a higher-rankingswitching means on the basis of an input manually effected by anoperator.

[0004] FR-2 621 176 discloses an ignition detector for ignition cellswherein a piston movable in a hollow member can be moved between aquiescent position and a locking position, and whereby an electricalcircuit is closed when the piston is in the quiescent position and isopened when the piston is in the locking position.

[0005] The subject matter of the application is based on the problem ofspecifying a circuit arrangement and method for the operation of thecircuit arrangement with which the point in time of the initialcommissioning of a backup battery can be unambiguously identified or,respectively, with which the end of the service life of the backupbattery can be unambiguously marked.

[0006] The problem is solved by an arrangement according to claim 1 or,respectively, by a method according to claim 9.

[0007] The subject matter of the application avoids an uneconomical,premature replacement of a backup battery that, moreover, is accompaniedby unnecessary ecological pollution.

[0008] Further advantageous developments of the subject matter of theapplication are recited in the subclaims.

[0009] According to a specific method for recognizing the end of theservice life of a backup battery in a circuit arrangement wherein abackup battery arranged in common and an element that is permanentlyirreversible with respect to electrically interrogatable quantities onthe basis of a power surge are replaceable, the following method stepsare established:

[0010] determination of the maximum amount of charge that can be takenfrom the backup battery;

[0011] setting the element into the irreversible condition when themaximum amount of charge that can be taken falls below a predeterminedlimit value.

[0012] Upon interrogation of the element, this measure makes it possibleto unambiguously distinguish a backup battery that has reached the endof its service life.

[0013] According to a particular embodiment of the subject matter of theapplication, the backup battery comprises two elements. This measureyields both an unambiguous determination of the point in time of theinitial commissioning of a backup battery as well as an unambiguousdistinguishability of the backup battery that has reached the end of itsservice life.

[0014] The subject matter of the application is described as anexemplary embodiment in greater detail below on the basis of two Figuresand in a scope necessary for understanding.

[0015] Thereby shown are:

[0016]FIG. 1 a circuit arrangement of the invention having a processorcomprising a bidirectional port; and

[0017]FIG. 2 a circuit arrangement of the application having a processorcomprising a unidirectional port.

[0018] In the Figures, elements reference identically have the samefunctions.

[0019] In the circuit arrangement of FIG. 1, a processor P monitors abackup battery Ak for buffering the operating voltage of a circuitarrangement. The backup battery can be established by a primary elementor by a secondary element. It is assumed below that the backup batteryis established by an accumulator such as, for example, a nickel-cadmiumaccumulator or a nickel hydride accumulator. The terminal of theaccumulator comprising the low potential (−) is connected to the one endof an element SI that is permanently irreversible with respect toelectrically interrogatable quantities on the basis of a power surge.The element SI can be established by any type of element thatpermanently changes its electrically interrogatable properties due to apower surge. For example, the element can be a bistable electromagneticrelay whose excitation winding lies in series with a break contact. Itis assumed below, that the element is established by a melt fuse. Theaccumulator and the element can be connectable to terminal posts byseparate lead wires. In the exemplary embodiment of FIG. 1, the terminalof the accumulator exhibiting the low potential as well as the one endof the melt fuse are connected to a releasable terminal post P3, theother end of the melt fuse is connected to a releasable terminal postP2, and the terminal of the accumulator exhibiting the high potential(+) is connected to a releasable terminal post P1. Together with themelt fuse and the appertaining terminals, the accumulator forms aaccupack AP. The terminal post P3 is connected to the referencepotential GND of the circuit arrangement via a terminal post P6. Theterminal post P1 is connected to a terminal accu-voltage ACV via aterminal post P4. In a circuit arrangement (not shown in detail) that issupplied with emergency power via a backup battery, the terminal postACV forms the connecting point for the backup battery. Let the circuitarrangement (not shown in detail) be established by a radio-supportedsubscriber telecommunication terminal means that is connectable to ahigher-ranking switching means via a radio interface according to theDECT standard in the framework of the radio-in-the-loop technology. Theterminal post P2 is connected to a bidirectional port bi of a processorP via a terminal post P5. The port bi is connected to a terminal VDC viaa high-impedance resistor R3, which may exhibit a resistance value of100k, said terminal VDC exhibiting an operating voltage potential thatlies above the reference potential GND.

[0020] The port is interrogated after a potential replacement of thebackup battery. Given a low voltage level at the port, a conclusion isdrawn that it is a new accupack and, given a high voltage level, aconclusion is drawn that it is a used accupack. A potential replacementof the backup battery can be established by a resetting of the circuitarrangement or in a cyclical interrogation. Of course, a potentialreplacement of the backup battery is also established when the circuitarrangement to be protected against a voltage outage determines acollapse of the backup voltage at the post ACV—while it is beingsupplied via the regular voltage supply—and derives a replacement of thebackup battery by a new one therefrom. As reaction to a recognizedreplacement of the backup battery, let the processor store the point intime of the installation of the backup battery. The point in time of theinstallation of the new backup battery can be reported to ahigher-ranking means (central), the switching means in the exemplaryembodiment, and can be further-processed thereat.

[0021] After detection of the installation of a new backup battery, thefuse is destroyed by being charged with a power surge. According to theexemplary embodiment of FIG. 1, a fuse is provided that is so sensitivethat it can be immediately destroyed by the current supplied at theoutput of the processor.

[0022] When the element SI exhibits the irreversible condition in aninterrogation, i.e. the melt fuse is high-impedance, then it isconcluded therefrom that the accumulator is not new.

[0023] According to a particular development of the subject matter ofthe application, the maximum charge amount that can be drawn from thebackup battery is identified, and the irreversible element is placedinto the irreversible condition when the maximum charge amount that canbe drawn falls below a predetermined limit value.

[0024] The circuit arrangement according to FIG. 2 collaborates with theaccupack AP from FIG. 1, whereby the terminal posts P1, P2 and P3 areconnected to the posts P7, P8 and P9. The terminal post P8 is connectedto a terminal IN of the processor that exhibits input functions. Aterminal post VCC, which exhibits an operating potential lying above thereference potential GND, is connected to the terminal post P8 via ahigh-impedance resistor R7, which may be assumed to have a value ofresistance of 100k. A transistor T1, which may be assumed to beestablished by a pnp-transistor of the type BC857c, and a resistor R6that exhibits a value of resistance of 150 Ohms are connected parallelto the resistor R7, whereby the emitter of the transistor is connectedto the terminal post VCC and the collector of the transistor isconnected to the resistor R6. A resistor R8, which may be assumed tohave a value of resistance of 100k, has its two ends connected to theterminal post VCC or, respectively, to the base of the transistor T1. Aresistor R5, which may be assumed to have a value of resistance of 15k,has its two ends connected to the base of the transistor or,respectively, to a terminal of the processor OUT that exhibits an outputfunction. A low potential at the terminal of the processor OUT effectsan activation of the transistor T1, as a result whereof a power surgethat destroys the fuse can flow. The transistor stage thus has a driverfunction. The interrogation of the condition of the irreversible elementensues via the terminal IN; the power surge for destroying the melt fuseis effected by a low potential at the terminal OUT.

1. Arrangement for maintaining the operating voltage of an electricalcircuit, whereby a backup battery (Ak) and an element (SI) that ispermanently irreversible with respect to electrically interrogatablequantities on the basis of a power surge are combined to form areplaceable unit.
 2. Arrangement according to claim 1, characterized inthat the unit is connectable to the electrical circuit via lead wires.3. Arrangement according to claim 2, characterized in that the leadwires are combined in a plug connector secured against pole reversalthat can interact with a counter piece connector of the electricalcircuit.
 4. Arrangement according to one of the preceding claims,characterized in that the element (SI) is a melt fuse.
 5. Arrangementaccording to claim 4, characterized by a fuse that can be destroyed by acurrent intensity output at the terminal of a processor.
 6. Arrangementaccording to claim 4, characterized in that the electrical circuitcomprises a driver circuit formed with a transistor, and the fuse can bedestroyed by the current intensity deliverable by the driver circuit. 7.Arrangement according to one of the preceding claims, characterized inthat the backup battery is an accumulator.
 8. Arrangement according toone of the preceding claims, characterized in that two elements (SI) areprovided.
 9. Method for recognizing the installation of a new backupbattery in a circuit arrangement in which a backup battery arranged incommon and an element (SI) that is permanently irreversible with respectto electrically interrogatable quantities on the basis of a power surgeare replaceable, in accord wherewith a check is carried out to see ifthe element (SI) is in its original condition; when the element (SI) isin its original condition, the element (SI) is placed into theirreversible condition; the point in time of setting the element (SI)into the irreversible condition is stored.
 10. Method for recognizingthe end of the service life of a backup battery in a circuit arrangementwherein a backup battery arranged in common and an element (SI) that ispermanently irreversible with respect to electrically interrogatablequantities on the basis of a power surge are replaceable, whereby thefollowing method steps are provided: determining the maximum chargeamount that can be drawn from the backup battery; setting the element(SI) into the irreversible condition when the maximum charge amount thatcan be drawn falls below a predetermined limit value.